Miniaturized disc player

ABSTRACT

A pickup feeding apparatus is comprised of a first rack provided on a pickup supporting member supported so as to become movable along a guide shaft, a second rack provided slidably relative to the first rack, a drive force transmitting gear for transmitting a driving force of a driving source to the first and second racks, a spring member for spring-biasing one of the first and second racks to the other along the guide shaft of the first and second racks in such a direction that gear teeth of a gear of the drive force transmitting means which are meshed with the first and second racks are gripped. A disc player is also disclosed, in which a disc drive motor and a pickup feeding motor are provided on the same chassis and the disc drive motor is located on the chassis at the position above the pickup moving locus fed by the pickup feeding device.

This application is a continuation of application Ser. No. 07/947,988filed Sep. 21, 1992 now abandoned which is a continuation of Ser. No.07/701,814 filed May 17, 1991, now abandoned which was a division ofapplication Ser. No. 07/629,623 filed Dec. 18, 1990, now U.S. Pat. No.5,119,362 issued Jun. 2, 1992.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a disc player and, moreparticularly, to a pickup feeding apparatus for feeding an opticalpickup head.

2. Description of the Prior Art

Recently, a portable small disc player has been widely used as a discplayer, particularly, a compact disc player. A pickup feeding mechanismportion of such conventional portable small disc player is arranged asshown in a plan view forming FIG. 1.

Referring to FIG. 1, a pickup head 41 is provided to read out a recordedsignal from a disc (not shown), and this pickup head 41 is supported toa guide shaft 42 secured to a mechanical chassis (not shown) so as tomove along the guide shaft 42 in the radius direction of the disc asshown by an arrow A in FIG. 1.

The pickup head 41 is provided with a rack 43 at its side opposite tothe guide shaft 42. The rack 43 is meshed with an operation gear 44 thatis rotated by a pickup moving motor (not shown). When the operation gear44 is rotated by the motor, a rotational force of the operation gear 44is transmitted to the rack 43 to thereby feed the pickup head 41.

In the thus arranged pickup feeding apparatus, if a backlash (playbetween teeth) lies between the rack 43 and the operation gear 44, asufficient pickup servo characteristic cannot be obtained. Therefore,the rack 43 is constructed as a so-called double rack structure in orderto prevent the vibration from being caused due to the backlash. Thisdouble rack structure will be explained below with reference to FIG. 2.

As shown in FIG. 2, the rack 43 is composed of a first rack 43a securedto the pickup head 41 and a second rack 43b slidable relative to thefirst rack 43a in the direction parallel to the pickup head movingdirection. The second rack 43b is spring-biased in one direction by aspring member (compression coil spring) 45 so that teeth of theoperation gear 44 are caught by the teeth of the two racks 43a and 43b,thereby removing the backlash.

As described above, in the pickup feeding apparatus of the standard discplayer, the rack must be constructed as the double rack structure inorder to remove backlash occurring between the rack and the operationgear, and the spring member must be provided in order to spring-bias onerack, which requires a spacing of this spring member. This hinders thepickup feeding apparatus from being miniaturized.

Incidentally, a drive mechanism of a disc player is generally comprisedof a disc drive mechanism for rotating a disc and a pickup feedingmechanism for feeding a pickup device which reads out a signal from thedisc.

The disc drive mechanism and pickup feeding mechanism include motors anddrive circuits for controlling these motors, respectively.

Considering the arrangement in which the motors and the drive circuitsare provided in the disc player, the motors and the drive circuits areindependently mounted on the disc player. To be more concrete, the motorfinished as one motor unit is attached to the mechanical chassis and thedriving circuit for this motor is mounted on a circuit board which isattached to the mechanical chassis at its portion different from that ofthe motor.

As earlier stated, the portable thin-type disc player has become verypopular recently and it is requested that the disc player be madecompact in size and be greatly reduced in thickness. However, since themotor and the circuit board are independently provided in theconventional disc player as described above, unavoidably the disc playercannot be miniaturized in size and reduced in thickness as is expected.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide animproved pickup feeding apparatus in which the aforenoted shortcomingsand disadvantages encountered with the prior art can be eliminated.

More specifically, it is an object of the present invention to provide apickup feeding apparatus in which space can be saved.

It is another object of the present invention to provide a pickupfeeding apparatus in which mechanisms can be more miniaturized.

It is still another object of the present invention to provide a pickupfeeding apparatus in which freedom can be increased from a designstandpoint.

It is a further object of the present invention to provide an improveddisc player which can remove the above-mentioned shortcomings anddisadvantages of the prior art.

It is yet a further object of the present invention to provide a discplayer in which spaces for locating motors and circuit boards can besaved considerably.

It is still a further object of the present invention to provide a discplayer which can be more miniaturized and which can be greatly reducedin thickness.

According to a first aspect of the present invention, a pickup feedingapparatus is comprised of a first rack provided in a pickup supportingmember supported so as to become movable along a guide shaft, a secondrack provided slidably relative to the first rack, a drive forcetransmitting gear for transmitting a driving force of a driving sourceto the first and second racks, a spring member for spring-biasing one ofthe first and second racks to the other along the guide shaft of thefirst and second racks so that gear teeth of the drive forcetransmitting means are caught by teeth of the first and second racks.

In accordance with a second aspect of the present invention, a discplayer is also disclosed, in which a disc drive motor and a pickupfeeding motor are provided on circuit boards secured to a chassis andone of a coil and a magnet of each of the motors is mounted on thecircuit boards.

The above, and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof illustrative embodiments to be taken in conjunction with theaccompanying drawings, in which like reference numerals are used toidentify the same or similar parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating an example of a conventional pickupfeeding device;

FIG. 2 is a schematic diagram showing a double rack structure of theconventional pickup feeding device;

FIG. 3 is a fragmentary perspective view illustrating a main portion ofan embodiment of a pickup feeding device according to the presentinvention in an exploded fashion;

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a perspective view of a disc drive mechanism of a disc playerto which the present invention is applied;

FIG. 6 is an exploded perspective view of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference toFIGS. 3 to 6.

As shown in FIGS. 5 and 6, there is provided a disc drive mechanism 1 ofa portable disc player and of which mechanism parts are mounted on amechanical chassis 2. A plurality of supporting apertures 3 are boredthrough the mechanical chassis 2, and the mechanical chassis 2 issupported at its supporting apertures 3 to an outer casing of the discplayer by means of a spring member (not shown) in a floating condition.

A disc drive mechanism and a pickup feeding mechanism are arranged onthe mechanical chassis 2, and the disc drive mechanism and the pickupfeeding mechanism will be described more fully below. As shown in FIG.6, the mechanical chassis is formed with first and second plate portions2a, 2b and an opening 2c. The disc drive mechanism is constructed asfollows.

Referring to FIGS. 5 and 6, a turntable 4 is provided to hold thereon adisc (not shown), and this turntable 4 is rotatably supported to abearing portion 6 implanted on the first plate portion 2a the mechanicalchassis 2 by means of a shaft 5 protruded from the central portion ofthe turntable 4. In the turntable 4, a plurality of supporting ballmembers 7 are resiliently protruding from the circumferential surfacearea of a central convex portion 4a of the turntable 4, which is engagedwith the central aperture of the disc so that, when the central apertureof the disc is engaged into the central convex portion 4a of theturntable 4 against the resilient force of the supporting ball members7, the disc can be simply and reliably supported on the turntable 4.

As shown in FIGS. 5 and 6, a motor 8 is provided to rotate the turntable4 and this motor 8 is directly constructed on a circuit board 9 on whicha motor driving circuit for the motor 8 is formed. More specifically,the circuit board 9 on which motor driving circuit assembly parts aremounted is secured to the mechanical chassis 2 by a screw 10, and astator coil 8a of the motor 8 is secured to the circuit board 9, while arotor magnet 8b is secured to the lower surface of the turntable 4 in anopposing relation to the stator coil 8a.

As shown in FIG. 6, the circuit board 9 has formed therethrough anescape aperture 11 into which the bearing portion 6 is inserted, wherebythe circuit board 9 can be located under the turntable 4 withoutdisturbing the bearing portion 6, thus the space being saved.

On the other hand, the pickup feeding mechanism is arranged as follows.

As shown in FIGS. 3 to 5, a pickup device 12 has an objective lens 12aprovided on an upper surface thereof, and a signal recorded on the discis read out by laser beams emitted through the objective lens 12a.

The pickup device 12 is supported by a guide shaft 13 secured to themechanical chassis 2 so that the pickup device 12 can be moved along theguide shaft 13 and through the opening 2c in the radial direction of thedisc.

The pickup device 12 is moved by a motor 14. As shown in FIGS. 5 and 6,a gear 15 is attached to the motor 14 and this gear 15 is meshed with anoperation gear 19 through a plurality of reduction gears 16, 17 and 18.These reduction gears 16, 17 and 18 and the operation gear 19 arepivotally supported by shafts 16a, 17a, 18a and 19a implanted on thesecond plate portion 2b of the mechanical chassis 2, respectively, asshown in FIG. 6.

As shown in FIGS. 3 to 5, a rack 20 is provided on the pickup device 12side, and this rack 20 is meshed with the operation gear 19, whereby therotational force of the motor 14 is transmitted to the rack 20 throughthe reduction gears 16, 17, 18 and the operation gear 19, thus thepickup device 12 being moved.

Similarly to the above-mentioned disc drive motor 8, the motor 14, asthe driving source of the pickup device 12, is directly constructed on acircuit board 21 on which its drive circuit is formed. Morespecifically, as shown in FIG. 6, the circuit board 21 on which pickupfeeding circuit assembly parts are mounted is secured to the mechanicalchassis 2 by means of screws 22, and a stator coil 14a of the motor 14is secured on this circuit board 21, while a rotor magnet 14b isrotatably supported to a bearing portion 23 implanted on the secondplate portion of the mechanical chassis 2 by a shaft 14b1 protruded fromthe central portion of the rotor magnet 14b in an opposing relation tothe stator coil 14a. The gear 15 which is meshed with the reduction gear16 is integrally secured to the central portion of the upper surface ofthe rotor magnet 14b.

The circuit board 21 has formed therethrough escape apertures 24 and 25into which the shafts 16a to 19a and the bearing portion 23 areinserted, respectively, whereby the circuit board 21 can be located onthe second plate portion of the mechanical chassis 2 without disturbingthe shafts 16a to 19a and the bearing portion 23. Thus space is savedand the player is miniaturized.

While in this embodiment coils of the motors are secured to the circuitboards, reverse arrangements are also possible. That is, the magnets maybe secured to the circuit boards. As shown in FIG. 6, a flexible cable50 establishes an operative electrical connection between circuit board9 and circuit board 21.

As described above, according to the disc player of this embodiment,since the disc drive motor 8 and the pickup feed motor 14 are directlyarranged on the circuit boards 9 and 21 which are secured to themechanical chassis 2, the spacing in which the motors 8 and 14 and so onare located can be considerably saved and the disc player can be maderemarkably smaller in size and reduced in thickness.

The construction of the rack 20 in the pickup feeding mechanism portionwill be explained.

As shown in FIG. 3, the rack 20 is composed of a first rack 20a securedto the pickup device 12 by means of screws 26 and a second rack 20bslidable relative to the first rack 20a in the direction parallel to thepickup feeding direction. That is, the rack 20 is constructed as aso-called double rack.

The first rack 20a has formed therethrough an insertion through-hole 27into which the guide shaft 13 is inserted. In other words, according tothe arrangement of this embodiment, the pickup device 12 is supported tothe guide shaft 13 by means of the first rack 20a.

The second rack 20b is spring-biased to the first rack 20a by acompression coil spring 28 in one direction parallel to the pickupfeeding direction, thereby preventing the rack 20 and the operation gear19 from being vibrated due to backlash therebetween.

The compression coil spring 28 for removing the backlash is provided onthe first rack 20a at its position through which the guide shaft 13 isinserted. More precisely, according to this embodiment, an accommodatingconcave portion 29 is formed on the first rack 20a by cutting away theintermediate portion of the insertion aperture 27. The compression coilspring 28 is inserted into this accommodating concave portion 29 and theguide shaft 13 is inserted into the compression coil spring 28 as shownin FIG. 4.

As shown in FIG. 4, the compression coil spring 28 acts in the expandingdirection between an engaging member 30 protruded on the second rack 20band one end face of the accommodating concave portion 29 to therebyspring-bias the second rack 20b in one direction (in the left of FIG. 4)parallel to the guide shaft 13. Consequently, the teeth of the operationgear 19 are caught by the teeth of the two racks 20a and 20b, therebyremoving the backlash.

As described above, according to this embodiment, since the pickupdevice 12 is supported by the guide shaft 13 by means of the rack 20 andthe compression coil spring 28 for removing backlash is provided withinthe rack 20 at its position in which the guide shaft 13 is inserted intothe compression coil spring 28, the space can be utilized effectivelyand as a result, the pickup feeding device can be miniaturized more.

As set out above, according to the pickup feeding device of the presentinvention, since the spring member for removing the backlash is providedwithin the rack at its position in which the guide shaft is insertedinto the spring member, the space occupied by the spring member can besubstantially removed and the space can be saved as compared with theprior art accordingly. There is then the advantage that the pickupfeeding device can be miniaturized more.

Further, in the pickup feeding apparatus of this embodiment, since thespring member is inserted by the guide shaft, the spring member can beprevented from being disengaged from the rack without a complicatedspring supporting mechanism. In actual practice, there can be achievedvarious effects, such as the miniaturized mechanism, increased freedomin designing and so on.

Furthermore, according to the disc player of the present invention,since the disc drive motor and the pickup feed motor are respectivelyprovided on the circuit boards secured to the chassis, the space withinthe disc player can be saved considerably so that the entirety of thedisc player can be miniaturized as compared with the conventional discplayer.

Furthermore, since each of the motors is arranged such that either ofthe coil and magnet is secured to the circuit board, the disc player ofthe present invention can be reduced in thickness as compared with theconventional disc player in which the motor finished as the motor unitis secured to the mechanical chassis.

In addition, since the motors and the circuit boards are integrallyformed, the assembly process can be reduced and hence the disc player ofthe present invention can be manufactured at low cost. Also, a freedomin designing can be increased.

Having described preferred embodiments of the present invention withreference to the accompanying drawings, it is to be understood that theinvention is not limited to those precise embodiments of the inventionand that various changes and modifications thereof could be effected byone skilled in the art without departing from the spirit or scope of thenovel concepts of the invention as defined in the appended claims.

I claim as my invention:
 1. A disc drive mechanism mounted on amechanical chassis comprising:a mechanical chassis formed with anopening and first and second plate portions; a turntable for supportinga disc, said turntable being rotatably mounted to said first plateportion of said chassis; a turntable motor for rotating said turntableincluding a first rotor magnet and a first stator coil; a first circuitboard which is discrete from said chassis and located beneath saidturntable, said first circuit board being deteachably mounted to saidfirst plate portion of said chassis; a pickup device capable of movingin said opening and translationally with respect to said turntable; apickup device motor for moving said pickup device translationally, saidpickup device motor including a second rotor magnet and a second statorcoil which are mounted on said second plate portion of said chassis; asecond circuit board which is discrete from said first circuit board,said second circuit board being detachably mounted to said second plateportion of said chassis and connected to said first circuit board by acable; and a plurality of gears rotatably mounted on said second plateportion via said second circuit board and connected between said pickupdevice motor and said pickup device; wherein either of said first rotormagnet and said first stator coil are mounted to said first circuitboard and either of said second rotor magnet and said second stator coilare mounted to said second circuit board.
 2. The disc drive mechanism ofclaim 1, wherein said turntable is mounted to said chassis by a bearingmeans and said first circuit board includes a hole for receiving saidbearing means wherein said first circuit board is located below saidturntable.
 3. The disc drive mechanism of claim 1, wherein said pickupdevice includes a rack means formed along one side thereof and gears areprovided to transmit force from said pickup device motor to said rackmeans to move said pickup device translationally.
 4. The disc drivemechanism of claim 3, wherein said gears are mounted on shafts and saidsecond circuit board includes holes for receiving said shafts.
 5. Thedisc drive mechanism of claim 4, wherein said rack means includes afirst and second rack connected by a spring means to ensure engagementwith said gears.